From my experience with the rapid rise rear derailleur was from decades ago in the 1990's, when a friend of mine, Garrett Polehonka, a former Suntour regional sales manager handed me a rear derailleur.
"Here try this !"
I swapped out my first generation Suntour Cyclone rear derailleur and mounted this Shimano Rapid Rise derailleur. I rode around the block.
Mind you, I have had been riding my favorite road bike with a first generation Suntour Cyclone front and rear derailleurs since 1973 with a lot of varied mileage from steep hills to flat terrain.
Upon shifting with this Rapid Rise rear derailleur, I instantly disliked it immediately proclaiming that it was all backasswards ! ! !
Needless to say, it had a very short life on my road bike. I returned it to my friend.
I am not a fan of the Rapid Rise rear derailleur in all of my profound stubbornness for change.
However, I am glad to see a large following of these Rapid Rise rear derailleurs in supporting Rivendell Bicycle Works.
Kim Hetzel